Membrane filtration is a standard step in many methods of analyzing a liquid sample for the presence of biological organisms. Such analyses are commonly performed in the interest of, for example, food safety, water quality, and/or environmental monitoring and/or study. Many membranes having an average pore size of 0.45 μm or less (e.g., cellulose acetate, nylon, etc. membranes) may be able to trap bacteria and allow growth of the trapped bacteria when placed on a suitable medium. It can be difficult, however, to recover bacteria from such membranes. These membranes, despite having an average pore size of 0.45 μm or less, typically possess a significant number of pores at the membrane surface that are larger than the biological organisms and, therefore, have torturous pore structure into which biological organisms may become trapped.